Existing solutions for retrofitting a power monitoring system in an electrical installation, include use of clamp-on current transforms (CTs) with current output of 1 or 5 amperes, requiring the wiring of the CTs, shorting block, voltage input connections, voltage disconnect and voltage protection device. In a three-phase, four-wire circuit, this solution requires more than 30 wires with 61 connection points. Use of clamp-on electronic CT's reduces the safety hazard of the standard CT, eliminating the need for shorting blocks. However, in a three-phase, four-wire configuration, this solution still requires more than 22 wires with 45 connection points. Another limitation of this solution is decreased system accuracy, as the low-voltage-output CT's have lower accuracies than standard CT's, thus, reducing the overall accuracy of the power monitoring system.
Clamp-on metering devices (e.g., “Enercept” devices) are commercially available, but have significant limitations, including the requirement for an external connection for voltage inputs, poor accuracy (e.g., due to poor repeatability of the positioning of the conductor inside the CT), and the need for dedicated part numbers for a single solution (e.g., the “Enercept” comes with three CT's and cannot address single-phase applications. In addition, with this solution the meter and CT's are factory assembled, which, after installation, results in CT's and wires hanging from the main conductors.